Month: April 2012

In spring time the world fills with green budding sprouts, new leaves, and bright flowers. But here in San Francisco a popular tree is budding that breaks the mold. Commonly called the Red Dragon or Japanese Maple tree this fiery redhead is in a class all her own.

Actually from New Zealand, the Red Dragon has long been prized for its unique leaf coloration, and humans have taken it with them around the world. But the more we see them around San Francisco the more we have been wondering: why? We all learned in school that plants have a green pigment called chlorophyll which is integral to photosynthesis, turning sunlight into energy the plant can use. The Times sums it up nicely here:

“Green plants… in their own simple and mysterious way utilize the energy of sunlight to convert carbon dioxide and water into food. Chief agent in this process of photosynthesis is chlorophyll, the green coloring-matter in leaves, which acts as a catalyst, speeding up the transformation, but undergoing no conversion itself.”

This trees bright red existence challenges our logic – no green pigment equals no photosynthesis right? How could that be? They grow just like every other plant. So the chlorophyll must be hiding under a mix of other pigments in the leaves. And in fact with a bit of research this is what we find.

“The green colour of chlorophyll is simply being masked by one of a number of other pigments not involved in photosynthesis, including flavins and carotenoids, which are present in abundance in certain species of plant.

Carotenoids are yellow and orange (they give carrots their orange colour…) or orange/red in colour, so probably contribute to the red colour of leaves, but the richness of the red colour is provided by flavins. These are a group of photoreceptor chemicals which absorb blue wavelengths of light from the spectrum … and emit all other wavelengths, making the pigment appear red.”

With their challenged ability to directly expose their chlorophyll to sunlight the Japanese Maple has a much slower growth rate than their green siblings. In an unprotected natural setting, the trees would rarely thrive. Horticulturists have carefully nurtured this beautiful species placing them in settings where the competition for light is minimal as the inch their way toward maturity.

The colors around us reveal exciting questions if we just take a moment to see them!

Last week we delved in to the rich world of structural color. We saw how nature uses structures smaller than wavelengths of light to create beautiful iridescent colors. Drawing inspiration from nature an artist here in San Francisco is making structural color all her own.

Kate Nichols actually synthesizes her own nano particles to create the color in her artwork. She wanted to paint with the colors of butterfly wings, but as we now know that is not possible with pigments. She is now using the latest advances in the material sciences.

“In 2008, she joined the Alivisatos Lab at the University of California at Berkeley as the lab’s first artist in residence. There, she synthesizes nanoparticles that exhibit structural color and creates macroscale art with them. Working as a painter, Kate became fascinated by the phenomenon of structural color–color that derives from a substance’s geometric structure rather than its chemical composition. Such structures must be roughly on the scale of wavelengths of visible light and, as such, are measured in nanometers, manipulable with nanotechnology, and out-of-reach in a typical painting studio.”

In this video from the Science on the Spotseries from KQED Nichols talks about her transition from chemical to structural color.